With the release of iOS 4.2 yesterday Mobile Safari has been upgraded to support WebSocket, along with some other new features too.
I have been reasonably vocal about how WebSocket isn’t the answer to everything, mainly due to browser support and the time it takes for large companies to upgrade their browsers and operating systems. However, on mobile devices this might not be such an issue and WebSocket could now be a good option for real time web apps on mobile devices. I would still advocate using a product that wraps this up and handles backwards compatibility and browser differences across all desktop and mobile environments.